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|
use ide_db::{helpers::FamousDefs, RootDatabase};
use syntax::ast::{self, AstNode, NameOwner};
use crate::{AssistContext, AssistId, AssistKind, Assists};
// Assist: generate_default_from_enum_variant
//
// Adds a Default impl for an enum using a variant.
//
// ```
// enum Version {
// Undefined,
// Minor$0,
// Major,
// }
// ```
// ->
// ```
// enum Version {
// Undefined,
// Minor,
// Major,
// }
//
// impl Default for Version {
// fn default() -> Self {
// Self::Minor
// }
// }
// ```
pub(crate) fn generate_default_from_enum_variant(
acc: &mut Assists,
ctx: &AssistContext,
) -> Option<()> {
let variant = ctx.find_node_at_offset::<ast::Variant>()?;
let variant_name = variant.name()?;
let enum_name = variant.parent_enum().name()?;
if !matches!(variant.kind(), ast::StructKind::Unit) {
cov_mark::hit!(test_gen_default_on_non_unit_variant_not_implemented);
return None;
}
if existing_default_impl(&ctx.sema, &variant).is_some() {
cov_mark::hit!(test_gen_default_impl_already_exists);
return None;
}
let target = variant.syntax().text_range();
acc.add(
AssistId("generate_default_from_enum_variant", AssistKind::Generate),
"Generate `Default` impl from this enum variant",
target,
|edit| {
let start_offset = variant.parent_enum().syntax().text_range().end();
let buf = format!(
r#"
impl Default for {0} {{
fn default() -> Self {{
Self::{1}
}}
}}"#,
enum_name, variant_name
);
edit.insert(start_offset, buf);
},
)
}
fn existing_default_impl(
sema: &'_ hir::Semantics<'_, RootDatabase>,
variant: &ast::Variant,
) -> Option<()> {
let variant = sema.to_def(variant)?;
let enum_ = variant.parent_enum(sema.db);
let krate = enum_.module(sema.db).krate();
let default_trait = FamousDefs(sema, Some(krate)).core_default_Default()?;
let enum_type = enum_.ty(sema.db);
if enum_type.impls_trait(sema.db, default_trait, &[]) {
Some(())
} else {
None
}
}
#[cfg(test)]
mod tests {
use crate::tests::{check_assist, check_assist_not_applicable};
use super::*;
#[test]
fn test_generate_default_from_variant() {
check_assist(
generate_default_from_enum_variant,
r#"
//- minicore: default
enum Variant {
Undefined,
Minor$0,
Major,
}
"#,
r#"
enum Variant {
Undefined,
Minor,
Major,
}
impl Default for Variant {
fn default() -> Self {
Self::Minor
}
}
"#,
);
}
#[test]
fn test_generate_default_already_implemented() {
cov_mark::check!(test_gen_default_impl_already_exists);
check_assist_not_applicable(
generate_default_from_enum_variant,
r#"
//- minicore: default
enum Variant {
Undefined,
Minor$0,
Major,
}
impl Default for Variant {
fn default() -> Self {
Self::Minor
}
}
"#,
);
}
#[test]
fn test_add_from_impl_no_element() {
cov_mark::check!(test_gen_default_on_non_unit_variant_not_implemented);
check_assist_not_applicable(
generate_default_from_enum_variant,
r#"
//- minicore: default
enum Variant {
Undefined,
Minor(u32)$0,
Major,
}
"#,
);
}
#[test]
fn test_generate_default_from_variant_with_one_variant() {
check_assist(
generate_default_from_enum_variant,
r#"
//- minicore: default
enum Variant { Undefi$0ned }
"#,
r#"
enum Variant { Undefined }
impl Default for Variant {
fn default() -> Self {
Self::Undefined
}
}
"#,
);
}
}
|
